Comp Thumpr cam opinions

[hdff]

Anyone have a Comp Thumpr roller cam in their big block 402? A mechanic recommended one for mine . Trying to give the BB a little backbone and a nice sound. Also are there benefits to a roller over a flat tappet

[hugger6933]

Lots of bennys to roller in more ways than one[$$$]I think unless you change other things you may need less of a cam than the Thumper. I am not familiar with their spec but I seem to recall them being pretty big.
Now, don't get me wrong i love and I mean LOVE a comp cam and have recommended them on here before a bunch. In that 402 I would say stay around 270 to 280 ish range and that is still on the large side. If it were a small block I would say use their 268H it is great.
One thing you need to remember it is similar to the small block cam to size relationship does matter. For example the cam most would pick for a 350 might be a little on the small side for a small block 400 yet otherwise be quite large for a 305. But others will chime in maybe someone who has run that cam, but I like the comp company and its products. I am only about 75 miles from Memphis and have shopped inside their place before and even had them grind a "personal grind" once back in my racing days. Jim

[hdff]

Originally Posted by hugger6933

Lots of bennys to roller in more ways than one[$$$]I think unless you change other things you may need less of a cam than the Thumper. I am not familiar with their spec but I seem to recall them being pretty big.
Now, don't get me wrong i love and I mean LOVE a comp cam and have recommended them on here before a bunch. In that 402 I would say stay around 270 to 280 ish range and that is still on the large side. If it were a small block I would say use their 268H it is great.
One thing you need to remember it is similar to the small block cam to size relationship does matter. For example the cam most would pick for a 350 might be a little on the small side for a small block 400 yet otherwise be quite large for a 305. But others will chime in maybe someone who has run that cam, but I like the comp company and its products. I am only about 75 miles from Memphis and have shopped inside their place before and even had them grind a "personal grind" once back in my racing days. Jim

The thumper shows to be a 283THR7. I don't know much about cams that is why I'm trying to educate myself before I deside

[budman k20]

For someone to give you good cam advice they would need to know a lot more info about your setup. Things like static compression, quench, head flow numbers, rocker arm ratio, gearing, transmission, weight and what you are going to do with it. Comp cam's has a spread sheet you fill out and they will make a cam recommendation for you. I would call them.

[steveo70]

My advice comes from a recent experience. I would call them directly. I recently listened to the musclecar podcast that had an interview with a Comp tech that advised just that. I went through the same delimma last December for my 454 build. I decided to call Clay Smith directly. The experience was awesome and informative. we discussed my bore, stroke, compression; as well as, cylinder heads and valve choice not to mention tranny, gear ratio, and tire size. they not only helped me select a "matched" camshaft but also the correct valve springs, rocker arm ratio, headers and carburetor for my engines intent. I decided for the roller cam. It is more of an investment but I will make the sacrifice of other wants for the added horsepower, not to mention the longevity and peace of mind regarding todays oil concerns. Now that I am in my 40's I'm a one and done guy except for bolt on items of course. I hope this helps. Just give them a shout so you can spend more time wrenching than researching like I did. Good luck and keep us updated.

[steveo70]

Budman snuck in ahead of me. Great advice! and shorter than my post lol.

[hdff]

Thanks for all of the good info. No post is ever too long when good information is involved. All I know about the motor is what the PO told me about,which was it was rebuilt to stock specs , and had about 800 miles on the rebuilt which now has 3800 miles on it, except for an Edelbrock carburetor and electric fans. it has some rusty headers that I plan to replace somewhere down the road.I also may swap back to a Quadra jet. It has a 700r4 transmission and I had the rear end rebuilt and changed the gear to 3.73 Posi. I don't know any of the other specs on the motor so I assume they would be the stock numbers as it came from the factory with what the PO told me. I don't want it to be a race truck I just wanted to have a better sound and a little more pep I'm not real happy with the power that this 402 is putting out now. I know the cost of going roller will be a little bit more but I'm in my 50s and just want to do it right the first time and enjoy it.

[Mrturner1]

Your might catch some flak about the Thumpr cam, so be ready for that lol It's a pretty cool cam that makes decent power and obviously sounds great, but there are a lot of cams with similar profiles that make much more power and sound good too. The Thumpr line was created with the intention of building a cam that sounds radical, "and doesn't hurt performance", that's what Comp says anyway. I wouldn't buy a cam that's advertised to "not hurt performance" personally, but to each his own.

I just did my first top end on a 350 and used a Comp 280H Magnum flat tappet and it's an awesome cam all around. If I could do it again (and I will a year from now hehe) I would stick with the Comp Extreme Energy cams. They have a really great lopey idle, and they make VERY good power wherever you want it. Even the bigger XE cams like 292 and 305 don't fall on their face on the low end torque, which is typically what a big cam will do. Another great thing about the Extreme Energy cams is the exhaust is a bit bigger than the intake, which I like a lot. Not the case with my Magnum cam, intake and exhaust is the same.

As stated above, tell us what you do with the truck, gear ratio, compression, what heads, ect ect. All good info for making recommendations.

Matt

[Mrturner1]

Almost any cam that has a rough, lopey idle is going to require a little bit of stall. Are you willing to do a stall converter? That will definitely narrow down your choices

[hdff]

Originally Posted by Mrturner1

Your might catch some flak about the Thumpr cam, so be ready for that lol It's a pretty cool cam that makes decent power and obviously sounds great, but there are a lot of cams with similar profiles that make much more power and sound good too. The Thumpr line was created with the intention of building a cam that sounds radical, "and doesn't hurt performance", that's what Comp says anyway. I wouldn't buy a cam that's advertised to "not hurt performance" personally, but to each his own.

I just did my first top end on a 350 and used a Comp 280H Magnum flat tappet and it's an awesome cam all around. If I could do it again (and I will a year from now hehe) I would stick with the Comp Extreme Energy cams. They have a really great lopey idle, and they make VERY good power wherever you want it. Even the bigger XE cams like 292 and 305 don't fall on their face on the low end torque, which is typically what a big cam will do. Another great thing about the Extreme Energy cams is the exhaust is a bit bigger than the intake, which I like a lot. Not the case with my Magnum cam, intake and exhaust is the same.

As stated above, tell us what you do with the truck, gear ratio, compression, what heads, ect ect. All good info for making recommendations.

Matt

Well that's above my head guess I'll call the comp guys for a recommendation.
I just cruise her on the weekends to gatherings and such, she's not my daily and I never work her. As far as compression I don't know what ever stock is I guess, heads are stock, 3.73 Posi, headers, edilbrock for now but considering going back to qudrajet, 700r4 and I don't know what the converter is, 15" rally's with 255/70/15. I have a ticking under the pass side valve cover and a miss on hard exceleration and occasionally a back fire also so something is up and I am trying to educate myself before it goes to the shop.

Another question and this might be a dumb one but can the cam be replaced without removing the a/c condenser? I know the radiator has to come out. The reason I ask is because I just finished redoing my ac and I don't want to charge it if the condenser has to come out

[geezer#99]

If you have a tick in one valve cover and a miss and a once in awhile backfire, then you won't need to worry about moving your condensor.
Why you ask!!
Because those are all symptoms of a cam going flat.
The motor will be coming out for a total overhaul. All that fine metal gets in everything. Only way to do it is pull it, tear it down, hot tank, clean, clean, clean and then rebuild.
Any quick cam change now is a waste of time and money.

[special-K]

x2. We call it peeing into the wind. You don't want to be thumping on that old bottom end

[budman k20]

Well that's above my head guess I'll call the comp guys for a recommendation.
I just cruise her on the weekends to gatherings and such, she's not my daily and I never work her. As far as compression I don't know what ever stock is I guess, heads are stock, 3.73 Posi, headers, edilbrock for now but considering going back to qudrajet, 700r4 and I don't know what the converter is, 15" rally's with 255/70/15. I have a ticking under the pass side valve cover and a miss on hard exceleration and occasionally a back fire also so something is up and I am trying to educate myself before it goes to the shop.

Another question and this might be a dumb one but can the cam be replaced without removing the a/c condenser? I know the radiator has to come out. The reason I ask is because I just finished redoing my ac and I don't want to charge it if the condenser has to come out

If you can swing the condenser up enough you may not have to remove it. It's easier to remove it. Also it's really hard to troubleshoot problems described on the internet. I had the exact problems you described on one of my cars and it turned out to be a burned wire and a leaky exhaust gasket (that I swore was a ticking lifter) both caused by my headers. Headers can be a pain, you need to take more precautions when running them. If you get a backfire on accel. then its most likely the accel pump (needs more fuel on transition to WOT). Doing a compression check is a really good idea before you invest in a performance cam.

[Mrturner1]

Originally Posted by hdff

Thanks for all of the good info. No post is ever too long when good information is involved. All I know about the motor is what the PO told me about,which was it was rebuilt to stock specs , and had about 800 miles on the rebuilt which now has 3800 miles on it, except for an Edelbrock carburetor and electric fans. it has some rusty headers that I plan to replace somewhere down the road.I also may swap back to a Quadra jet. It has a 700r4 transmission and I had the rear end rebuilt and changed the gear to 3.73 Posi. I don't know any of the other specs on the motor so I assume they would be the stock numbers as it came from the factory with what the PO told me. I don't want it to be a race truck I just wanted to have a better sound and a little more pep I'm not real happy with the power that this 402 is putting out now. I know the cost of going roller will be a little bit more but I'm in my 50s and just want to do it right the first time and enjoy it.

Man this story sounds all to familiar lol I just got done doing a 350 freshening up myself. Same story, PO said the motor had less than 10k on a FULL rebuild. I tore it all down and sure enough the motor is pretty fresh. Put a big ole cam in it and some awesome heads, now it runs great and no smoke or blow-by. You could get lucky and have an honest PO, or you could put a cam in a tired motor and start smoking in a month or two.

[hdff]

Ok I found someone to do my work. He sounds like he know a lot about carburators and old motors. I do have another cam question, with a comp magnum 280h does anyone have any issues with vacuum? I'm considering either the 280h or the 270h. I'm also gonna put in a 2500 stall, Holley 750 and edilbrock rpm intake and new rocker arms. Also while all the work is going on going to put on a new set of headers. So if anyone has a 270 or 280 cam could you let me know if you have any vacuum issues.

Keith

[Mike C]

270. IMO, the 280 with it's 230 deg at .050 is too much for a truck that's not being built for street/strip. But a lot of this is how much can you/are you willing to put up with.

I'm rebuilding a 427 for my '69 short step. It's a 400 hp motor from a '69 Corvette. Will be 9.9:1 with big oval port but 101 cc heads. I have decided to run the smallest Nitrous Hydraulic Roller that Comp makes. It's 224/236 @ .050 and 113 LSA. My plan is to run it through some repro 'Vette manifolds after angle milling the drivers side for clearance. GM performance parts intake to keep it looking like a stock 427.

I chose this cam for the opposite reason you would get a Thumpr though. I want it to idle smoothly and have good low speed torque while being able to scavenge without running headers. For a 402 I would keep LSA 110 or above and duration at .050 less than 220 IME.

[hdff]

Called comp today and they recommended the 270 so that's what I'm going with

[Mrturner1]

I have the 280H and I love it. I actually wouldn't go any smaller to be honest. It likes a little bit of stall, screams from 2500-6500 and still has good low end. I drive mine all the time and it's fun, sound downright nasty, and it changed the whole feel of the truck.